EP0412097A1 - Systeme de detection a champ magnetique - Google Patents

Systeme de detection a champ magnetique

Info

Publication number
EP0412097A1
EP0412097A1 EP19890905156 EP89905156A EP0412097A1 EP 0412097 A1 EP0412097 A1 EP 0412097A1 EP 19890905156 EP19890905156 EP 19890905156 EP 89905156 A EP89905156 A EP 89905156A EP 0412097 A1 EP0412097 A1 EP 0412097A1
Authority
EP
European Patent Office
Prior art keywords
detectors
conductor
detection system
conductors
respect
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19890905156
Other languages
German (de)
English (en)
Inventor
Andrew John Highclare Highview Way Wilks
Peter Geoffrey Flaxley Mill Williams
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
OMEGA ELECTRIC Ltd
Original Assignee
OMEGA ELECTRIC Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB888809381A external-priority patent/GB8809381D0/en
Priority claimed from GB888815391A external-priority patent/GB8815391D0/en
Priority claimed from GB888824657A external-priority patent/GB8824657D0/en
Priority claimed from GB888826948A external-priority patent/GB8826948D0/en
Application filed by OMEGA ELECTRIC Ltd filed Critical OMEGA ELECTRIC Ltd
Publication of EP0412097A1 publication Critical patent/EP0412097A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
    • G01R33/025—Compensating stray fields
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R11/00—Electromechanical arrangements for measuring time integral of electric power or current, e.g. of consumption
    • G01R11/02—Constructional details
    • G01R11/24—Arrangements for avoiding or indicating fraudulent use

Definitions

  • This invention relates to a means for detecting external magnetic fields with the objective of nulling out the effect of the applied field. This is particularly useful in a solid state electricity meter. Solid state electricity meters, by virtue of their means of construction, can produce erroneous readings when subjected to a large external magnetic field.
  • a magnetic field detection system comprising a pair of detecting elements positioned with respect to a current carrying conductor within the system which will create a field to be measured and linked in a circuit such that the sum of the outputs of the detectors will be zero with respect to any output components thereof caused by a large field external to the system.
  • the sensors can be orientated so that they detect components of the magnetic field, as created by the current in the conductor, in the same sense. Their outputs can then be added to indicate the presence of a field due to the current flowing through the single conductor.
  • the detectors may be so orientated that they face in mutually opposite directions with respect to any external field. Alternatively they may face in the same direction, but the output of one will be fed to an invertor. Then when the outputs derived from the detectors are summed the effect caused by the external field will be nullified.
  • the two detectors may be placed in close proximity to the live and neutral conductors respectively of a current carrying system so that the fields created by the two conductors affect the detectors in the same sense, but any external field will affect the sensors in respective opposite senses.
  • Such an arrangement not only enables the passage of a current through the conductors to be detected, but also allows for the detection of any unauthorized tapping into one of the conductor lines which will therefore alter the normal flux fields created by the two conductors.
  • Solid state meters are most usually tampered with by two means, firstly by the application of a large external field and, secondly, by the injection of a fraudulent current through the live in and live out terminals.
  • This arrangement allows for detection of attempts to tamper with a solid state electricity meter, identification of the type of tampering taking place, and the ability to calculate correctly the actual power usage while the meter is being tampered with.
  • the various possible combinations of detectors in association with a pair of conductors are possible as will become apparent from the following description.
  • Figure 1 shows one embodiment of a magnetic field detection system of this invention comprising a pair of solid state detectors positioned with respect to . a current carrying conductor in a large external field;
  • Figure 2 shows a circuit which will combine the outputs of the two solid state detectors of Figure 1;
  • Figure 3 graphically shows the effect of the overall system of Figures 1 and 2;
  • Figure 4 illustrates a modification of the system shown in Figure 1;
  • FIG. 5 graphically shows the effect of the overall system of Figure 4 used in combination with Figure 2;
  • Figure 6 is a further modification of the system of Figure 1 used in association with a pair of current carrying conductors;
  • Figure 7 shows a system of this invention using three sensors positioned with respect to live and neutral conductors within a solid state electricity meter.
  • Figure 8 shows yet another system of this invention using two pairs of solid state sensors positioned with respect to live and neutral conductors within a solid state electricity meter.
  • a solid state sensor 1 such as a Hall effect device or a magneto resistive sensor, is placed in close proximity to a current carrying conductor 2.
  • a magnetic field 3 is generated by the current flowing in the conductor 2.
  • the sensor 1 is orientated so that for current flowing out of the end of the conductor 2 its output goes positive for this argument.
  • a second sensor 4 is placed some distance away from 1 but residing in the same vertical plane, and inverted so that for current flowing out of conductor 2 its output goes negative.
  • the magnitude of the output of sensor 1 will be 10 times greater than that of sensor 4.
  • the effect on 1 will be to produce a negative output and at 4 a positive output.
  • the magnitude of the outputs will be equal to all intents and purposes.
  • V(l) is proportional to the flux due to the conductor plus the external field
  • V(4) is proportional to the flux of the external field
  • Trace 10 represents a flux with peak 0 values of +/- 1.5 mT induced at the surface of 2 by a true current in 2.
  • Trace 11 indicates the presence of a large external field of +/- 0.5 mT in antiphase to the field induced by the current in 2.
  • 12 indicates the output of 1 which sums the field due to the current in 2 and the large external field.
  • Trace 13 indicates the output of 4 in response to the external applied field.
  • Trace 14 indicates the corrected signal at the output of the amplifier 9, which represents the original true flux due to the current in 2.
  • the second sensor 4 is placed at a distance equal to the distance of sensor 1 from the conductor 2 but diametrically opposite to sensor 1 and so orientated as to detect the field 3 in the same sense as sensor 1, but to detect the - field 5 in the opposite sense. Since the external flux 5 has an equal and opposite effect on sensors 1 and 4 the external effects are balanced out and the derived output is effectively twice that of one sensor in isolation.
  • Traces 10, 11 and 12 are as before Trace 15 indicates the output of 4 which sums the field due to the current in 2 and the large external field 5.
  • Trace 16 indicates the corrected signal at the output of amplifier 9 which represents the original true flux due to current in 2 (but at double the amplitude) .
  • Figure 6 shows the two detectors 1 and 4 positioned with respect to the live and neutral conductors 2 and 17 respectively of a current carrying system.
  • the sensors 1 and 4 are orientated so that the magnetic fields 3 and 18 generated by the current cause the two sensors to go positive for the arguments illustrated.
  • Both sensors lie in the same vertical plane, but since they are inverted with respect to each other the sensor 1 will produce a negative output component due to detection of a large external field 5, whilst the sensor 4 produces a corresponding positive output component.
  • the magnitude of these output components will, to all intents and purposes, be equal.
  • the arrangement shown in Figure 6 not only allows the passage of a current through the system incorporat- ing the two conductors 2 and 20 to be detected, but also enables unauthorized tapping into one of the conductor lines to be detected as this will alter the normal levels of the flux fields and create an abnormal summed output from the detector circuit.
  • two detectors 1 and 4 are placed in close proximity to the live 2 and neutral 17 conductors, whilst a third detector 19 is placed some distance from either, for example directly between the two conductors.
  • the two detectors 1 and 4 in close proximity to the conductors 1 and 17 will normally produce outputs which are equal in magnitude.
  • the third detector 19 will normally produce no output.
  • Each pair responds in a similar manner to an external field 5, such that the summed outputs of each pair are not affected by the external field, whilst each member of each pair is affected in an opposing manner.
  • each member of each pair is additive.
  • detectors 1 and 1A Upon application of a large external field 5 detectors 1 and 1A will generate similar signals as will 4 and 4A. Hence the difference between the output of 1 and 1A will be zero, as will the difference between 4 and 4A, while the sum of 1 and 4 will be zero, as will the sum of 1A and 4A. Hence if a magnitude difference occurs between 1 and 1A or between 4 and 4A, but the aforementioned criteria apply, then this is a unique indication of the application of an external field, but this external field will be corrected for automatically.
  • the sensors 1 and 4 are advantageously positioned radially of the conductors. Furthermore, where the 5 sensors are to be integrated into chips, the chips could be formed with suitable cut-outs to receive the proposed conductor(s) in precisely the required positions(s) . Another possible modification is to provide the two sensors so that they face in the same sense relative to the field 5, but incorporate in the circuitry an invertor for one of the (amplified) outputs from the sensors, so as to achieve the desired nullification of the flux measurement from the field 5, when the two outputs are combined later.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
  • Measuring Magnetic Variables (AREA)

Abstract

Un capteur solide (1), tel qu'un dispositif à effet de Hall, est placé à proximité étroite d'un conducteur (2) dans lequel s'écoule un courant. Un champ magnétique (3) est généré par le courant qui s'écoule dans le conducteur (2). Un deuxième capteur (4) est placé à une certaine distance du capteur, (1) mais sur le même plan vertical, et inversé de sorte que sa sortie devienne négative lorsque du courant sort du conducteur (2). Lorsque les sorties de (1) et (4) sont additionnées, la sortie combinée ne représente que le flux dû au conducteur, car les deux mesures dues à des champs externes s'annulent. On peut utiliser des systèmes modifiés avec des capteurs additionnels, surtout en association avec une paire de conducteurs dans un système qui transmet un courant, ce qui permet de détecter toute violation du système.
EP19890905156 1988-04-21 1989-04-21 Systeme de detection a champ magnetique Withdrawn EP0412097A1 (fr)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
GB8809381 1988-04-21
GB888809381A GB8809381D0 (en) 1988-04-21 1988-04-21 External magnetic field detection & nulling for solid state electricity meters
GB8815391 1988-06-28
GB888815391A GB8815391D0 (en) 1988-06-28 1988-06-28 External magnetic field detection & nulling technique whilst enhancing detection
GB8824657 1988-10-21
GB888824657A GB8824657D0 (en) 1988-10-21 1988-10-21 Magnetic field detection system
GB8826948 1988-11-17
GB888826948A GB8826948D0 (en) 1988-11-17 1988-11-17 Tamper detection & identification for solid state electricity meters

Publications (1)

Publication Number Publication Date
EP0412097A1 true EP0412097A1 (fr) 1991-02-13

Family

ID=27450080

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890905156 Withdrawn EP0412097A1 (fr) 1988-04-21 1989-04-21 Systeme de detection a champ magnetique

Country Status (3)

Country Link
EP (1) EP0412097A1 (fr)
JP (1) JPH03503930A (fr)
WO (1) WO1989010570A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2050608B1 (es) * 1992-09-25 1995-11-01 Amper Sa Dispositivo antifraude en contadores electronicos de energia electrica.
US6984978B2 (en) 2002-02-11 2006-01-10 Honeywell International Inc. Magnetic field sensor
GB2391948B (en) * 2002-08-15 2006-11-15 Pri Ltd Apparatus for detecting tampering with a utility meter
KR100632458B1 (ko) 2004-04-30 2006-10-11 아이치 세이코우 가부시키가이샤 가속도 센서
CN107110897A (zh) * 2015-01-08 2017-08-29 株式会社村田制作所 电流传感器

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932813A (en) * 1972-04-20 1976-01-13 Simmonds Precision Products, Inc. Eddy current sensor
JPS56122978A (en) * 1980-02-29 1981-09-26 Shimadzu Corp Magnetism exploring device
US4639674A (en) * 1983-04-11 1987-01-27 Schonstedt Instrument Company Apparatus and method employing extraneous field compensation for locating current-carrying objects
GB2183348B (en) * 1985-11-23 1989-10-04 Manchester Lasers Electricity meter

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO8910570A1 *

Also Published As

Publication number Publication date
JPH03503930A (ja) 1991-08-29
WO1989010570A1 (fr) 1989-11-02

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